AP Syllabus focus:
‘Slash-and-burn, terracing, irrigation, deforestation, wetland drainage, shifting cultivation, and pastoral nomadism alter landscapes.’
Agricultural practices reshape Earth’s surface as farmers modify terrain, vegetation, soils, and water systems to support food production under varying environmental and cultural conditions.
Major Forms of Landscape Modification
Human–environment interactions in agriculture often involve altering the physical landscape to increase productivity. These modifications can create long-term ecological change and reflect regional traditions, technologies, and economic priorities.
Slash-and-Burn Agriculture
Slash-and-burn agriculture is a swidden farming method in which vegetation is cut and burned to clear fields and release nutrients into the soil.
A hillside in Chiang Mai, Thailand, where trees have been cut and burned to clear land for cultivation. The ash-covered ground, exposed tree trunks, and surrounding smoke show how slash-and-burn rapidly transforms forest into temporary farmland. The remaining forest in the background is extra contextual detail that highlights the patchwork landscape created by shifting cultivation. Source.
Slash-and-Burn Agriculture: A land-clearing process that involves cutting vegetation and burning it to create temporarily fertile fields.
This practice is most common in tropical regions where soils are nutrient-poor but regenerate quickly with the ash layer. It forms the foundation of shifting cultivation, a subsistence system where fields are used briefly and then abandoned to recover fertility. After the initial burn, farmers plant crops such as cassava, maize, or upland rice. Overuse or shortened fallow periods, however, can lead to soil degradation, biodiversity loss, and increased carbon emissions.
Shifting Cultivation
Shifting cultivation relies on periodic landscape modification through clearing, burning, and rotation.
Shifting Cultivation: An extensive farming system in which farmers rotate fields rather than crops, allowing abandoned plots to naturally regenerate.
Shifting cultivation shapes large mosaic-like patterns on the landscape, as different fields exist in various stages of use or regrowth. This patchwork reflects a sustainable cycle when population densities remain low, but modern pressures often reduce fallow time, stressing ecosystems. The mobility of fields also limits permanent infrastructure development, influencing rural settlement patterns.
Terracing
Terracing converts steep slopes into level steps to reduce erosion and create arable land, especially in mountainous regions.
Terracing: A farming technique in which sloped land is reshaped into a series of flat, stepped surfaces to retain water and soil.
Terraces are most associated with rice cultivation in East and Southeast Asia, but they occur worldwide. By slowing runoff and capturing water, terracing allows farmers to grow water-demanding crops on steep terrain. This engineering profoundly alters hillsides, creating distinctive contour patterns visible from long distances.
Panoramic view of rice terraces stepping down steep mountain slopes in the Philippine Cordilleras. The terraces show how farmers cut and retain the slope into level steps that hold water and soil for rice cultivation, dramatically reshaping the original landform. The image also reflects UNESCO’s broader cultural heritage framing of the terraces, which goes beyond the AP syllabus but reinforces the idea of long-term human–environment interaction. Source.
Irrigation
Irrigation systems redirect and control water to support crop growth in arid or seasonally dry climates.
Irrigation: The artificial application of water to land to assist in the growing of agricultural crops.
Farmers use methods ranging from simple canals to advanced sprinklers and drip systems.
A center pivot irrigation system applies water across an extensive wheat field in the western United States. The long rotating pipeline and evenly spaced sprinklers demonstrate how mechanized irrigation redistributes water across the landscape, enabling intensive agriculture on otherwise dry land. The background sky and distant hills are additional scenic elements that are not central to the AP syllabus but help students visualize the broader environmental setting of irrigated fields. Source.
Irrigation expands agricultural land-use options and intensifies production but also risks soil salinization, a buildup of salts that damages fields. Large-scale irrigation infrastructures, such as dams and aqueducts, reshape hydrology by altering river flow, groundwater levels, and wetland areas. These systems can encourage settlement in previously marginal regions and foster commercial agriculture.
Deforestation
Deforestation occurs when forests are cleared for agricultural expansion, especially for cattle ranching, plantations, or shifting cultivation.
Deforestation: The large-scale removal of forest cover, typically to convert land for agricultural or other human uses.
This process transforms dense forest into open cropland or pasture, significantly altering carbon cycles, soil structure, and biodiversity. Deforested landscapes often experience increased erosion and reduced rainfall retention. In many regions, deforestation is closely tied to commercial agriculture, where global demand for commodities such as soy or palm oil drives rapid land-use conversion.
Wetland Drainage
Wetland drainage converts marshes, swamps, and bogs into usable farmland by removing or redirecting water.
Wetland Drainage: The process of removing water from wetland areas to create dry land suitable for agriculture.
Drainage reshapes ecosystems by eliminating natural water filtration and wildlife habitats. Drained wetlands are often highly fertile, making them desirable for intensive agriculture, especially vegetables and grains. However, these modifications can increase flooding risk downstream and reduce regional biodiversity. Once drained, wetlands are difficult to restore, making this modification one of the most ecologically permanent.
Pastoral Nomadism
Pastoral nomadism alters landscapes through the seasonal movement of livestock herds across large territories.
Pastoral Nomadism: A form of subsistence agriculture in which herders move domesticated animals seasonally in search of pasture and water.
Although this practice does not transform land mechanically, livestock grazing influences vegetation patterns and soil stability. Overgrazing near water sources or along migratory routes can reduce plant cover and accelerate desertification. Nomadic routes often follow traditional paths shaped by climate, water availability, and political boundaries, creating recognizable movement corridors across semi-arid landscapes.
Interpreting Landscape Modification in AP Human Geography
Landscape modifications reflect the interplay of cultural practices, environmental conditions, and economic goals. Understanding these processes helps explain rural settlement patterns, regional land-use systems, and the environmental consequences of agricultural activities.
FAQ
Environmental regulations often restrict burning seasons, limit the size of cleared areas, or require permits to reduce wildfire risk and protect biodiversity.
In wetland areas, drainage is frequently controlled by conservation laws that prevent the destruction of habitats critical for flood control or endangered species.
These restrictions can push farmers towards alternative techniques such as agroforestry, controlled grazing, or water-efficient irrigation.
Terracing requires consistent labour and upkeep; without maintenance, terraces collapse and slopes revert to erosion-prone conditions.
Key factors influencing long-term maintenance include:
• Availability of labour
• Economic returns from terrace-based crops
• Rural depopulation or shifts to urban employment
• Government support for traditional farming systems
When maintenance declines, landslides and soil loss can rapidly reshape the landscape.
Seasonal routes produce repeated grazing pressure that shapes vegetation composition along migratory corridors.
Over time, this leads to:
• Reduced plant height and diversity near watering points
• Distinctive trampling paths and soil compaction
• Patchy distribution of shrubs and grasses based on herd movement
These patterns remain visible long after herds leave, revealing historic land-use cycles.
Irrigation increases local humidity and evapotranspiration, introducing additional moisture into otherwise dry air.
Large irrigated fields may experience:
• Slightly lower daytime temperatures due to increased evaporation
• More frequent morning fog or dew
• Changes in local wind patterns caused by surface temperature differences
These microclimatic shifts can influence which crops can be grown and the timing of harvests.
Removing forest cover increases runoff and sediment flow into rivers, leading to higher turbidity and reduced water quality downstream.
Consequences can include:
• Greater risk of riverbank erosion
• Altered flood cycles as water reaches channels more quickly
• Disruption of aquatic habitats sensitive to sediment loads
These downstream impacts often extend far beyond the original agricultural clearing.
Practice Questions
Question 1 (1–3 marks)
Explain how slash-and-burn agriculture modifies the physical landscape.
Question 1
1 mark: Basic description that vegetation is cut and burned.
2 marks: Clear statement that burning releases nutrients and temporarily clears land for cultivation.
3 marks: Detailed explanation that the process replaces forest cover with open farmland, creating ash-covered soil and altering biodiversity or soil structure.
Question 2 (4–6 marks)
Discuss how terracing, irrigation, and pastoral nomadism each alter the physical landscape. In your answer, refer to differences in the type and extent of landscape modification created by these practices.
Question 2
1–2 marks: General description of any two of the three practices and their landscape impacts.
3–4 marks: Explanation of all three practices with clear reference to how each modifies landforms or vegetation (e.g., terracing reshapes slopes, irrigation redirects water, pastoral nomadism affects vegetation through grazing).
5–6 marks: Well-developed comparison showing differences in the type and extent of modification (e.g., terracing as a major structural change, irrigation as hydrological alteration, pastoral nomadism as biological/vegetation change), with accurate geographic understanding and clear written expression.
